1. Field of the Invention
This invention relates to an oil pump for supplying lubricating oil to a saw chain of a chain saw.
2. Description of the Prior Art
In an example of this type of conventional oil pump such as disclosed in U.S. Pat. No. 4,231,716, a worm engaging with and driven by a worm wheel and a rate adjusting cam are integrally formed with a pumping plunger by machining from a one-piece blank provided for the plunger.
To form this type of integral part for use in the conventional device, it is necessary to carry out different work processes with respect to one blank so as to form the tooth of the worm, the cam portion and so forth along with the work of forming the plunger. At the same time, these portions are required to be worked with high accuracy. Therefore it takes a large amount of labor to manufacture the pump, resulting in a high production cost.